Detail of GB/T 24733-2023

Introduction of GB/T 24733-2023

1 Scope This document specifies the material designation, order information, manufacturing process, technical requirements, sample preparation, test methods, inspection rules and marking, quality certificate, rust protection, packaging and transportation for austempered ductile iron castings. This document applies to ductile iron castings cast in sand moulds or moulds of comparable thermal behaviour and subjected to austempering. It may apply to austempered ductile iron castings produced by other casting processes, e.g., metal mould, metal mould coated with sand, shell mould, investment casting and continuous casting, as reference. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 223.3 Methods for chemical analysis of iron, steel and alloy - The diantipyrylmethane phosphomolybdate gravimetric method for the determination of phosphorus content GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium carbonate separation-diphenyl carbazide photometric method for the determination of chromium content GB/T 223.18 Methods for chemical analysis of iron, steel and alloy - The sodium thiosulfate separation iodimetric method for the determination of copper content GB/T 223.23 Iron steel and alloy - Determination of nickel content - The dimethylglyoxime spectrophotometric method GB/T 223.26 Iron steel and alloy - Determination of molybdenum content - The thiocyanate spectrophotometric method GB/T 223.58 Methods for chemical analysis of iron, steel and alloy - The sodium arsenite-sodium nitrite titrimetric method for the determination of manganese content GB/T 223.60 Methods for chemical analysis of iron, steel and alloy - The perchloric acid dehydration gravimetric method for the determination of silicon content GB/T 223.68 Methods for chemical analysis of iron, steel and alloy - The potassium iodate titration method after combustion in the pipe furnace for the determination of sulfur content GB/T 223.69 Iron steel and alloy - Determination of carbon contents - Gas-volumetric method after combustion in the pipe furnace GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature GB/T 229 Metallic Materials - Charpy Pendulum Impact Test Method GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method GB/T 5611 Foundry terminology GB/T 5612 Code for representing cast iron GB/T 5677 Castings - Radiographic testing GB/T 5678 Sampling methods of spectrochemical analysis for cast alloys GB/T 6060.1 Surface roughness comparison specimen - Part 1: Casting surface GB/T 6414 Castings - Dimensional tolerances and geometrical tolerances and machining allowances GB/T 9441 Metallographic test method for spheroidal graphite cast iron GB/T 9443 Steel and iron castings - Liquid penetrant inspection GB/T 9444 Steel and iron castings - Magnetic particle inspection GB/T 11351 Mass tolerances of casting GB/T 14203 General rules for spark discharge atomic emission spectrometry GB/T 15056 Casting surface roughness - Appraising method GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition GB/T 20125 Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method GB/T 24234 Stainless steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (Routine method) GB/T 34904 Spheroidal graphite iron castings - Ultrasonic testing 3 Terms and definitions For the purposes of this standard, the terms and definitions given in GB/T 5611 and the following apply. 3.1 austempered ductile iron; ADI ductile iron material, produced by austempering, which consists of predominantly ausferrite Note: Austempered ductile iron is also called “ausferritic ductile iron”. 3.2 austempering of ductile iron heat treatment process of spheroidal graphite cast iron, consisting of heating the castings to a temperature at which austenite starts to form during heating and holding a sufficient time for carbon diffusion into the austenite, followed by cooling at a rate sufficient to avoid the formation of pearlite, and transforming the matrix structure for a time and a temperature (above the martensite start temperature) sufficient to produce the desired properties 3.3 ausferrite ductile cast iron microstructure which consists of predominantly acicular ferrite and high carbon austenite 3.4 relevant wall thickness of casting section thickness of the casting to which the determined mechanical properties apply 3.5 side-by-side cast sample sample cast in the mould alongside the casting, with a joint running system 4 Designation of material 4.1 Austempered ductile iron materials shall be designated in accordance with GB/T 5612. 4.2 Austempered ductile irons are classified into six grades according to the minimum tensile strength and the minimum elongation after fracture determined on test pieces (L0=5d) machined from separately cast samples, side-by-side cast samples or cast-on samples, as shown in Table 1. Table 1 Mechanical properties of separately cast samples, side-by-side cast samples or cast-on samples Material designation Relevant wall thickness of casting t mm Tensile strength Rm MPa(min.) Proof strength Rp0.2 MPa(min.) Elongation after fracture A5 (L0=5d) %(min.) Elongation after fracture A4 (L0=4d) %(min.) QTD800-11 QTD800-11R t≤30 800 550 11 12 30

Contents of GB/T 24733-2023

Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Designation of material 5 Manufacturing process 6 Technical requirements 7 Test piece preparation 8 Test methods 9 Inspection rules 10 Marking, quality certificate, rust prevention, packaging, storage and transportation Annex A (Informative) Manufacturing process of austempered ductile iron castings Annex B (Informative) Unnotched impact test Annex C (Informative) Additional information on mechanical and physical properties Annex D (Informative) Performance characteristics and application examples by grades of austempered ductile irons Annex E (Informative) Guidance values for tensile strength and elongation after fracture for test piece cut from a casting Annex F (Informative) Guidance values for Brinell hardness Annex G (Normative) Sectioning procedure for cast samples Annex H (Informative) Cross-references of similar grades of austempered ductile irons Bibliography